Conor Watkins And J. David Rogers
Grand Canyon Research
Surprise Valley

The geologic map of the Grand Canyon  30' X 60' Quadrangle shows much of the extent of the Surprise Valley Landslide Complex, a series of Toreva block type slides with an estimated combined volume of over one cubic mile.

This photo taken in the late afternoon sun from the Esplanade shows some of the youngest landslides in Surprise Valley.  The Surprise Valley Landslide Complex is too large to comprehend from any one vantage point.

Cross sectional sketch of a typical Toreva Block in Surprise Valley with a log spiral shapped basal failure surface developed in the Bright Angel Shale.  Taken from "Geology of The Grand Canyon, 3rd Edition", 1979.

Ground view of three secondary landslides at the northern margin of Surprise Valley.  These slides initiated in the Bright Angel Shale and progressed up through the Supi Formations as sketched in the diagram above.

Another view of the three secondary slides, as seen from within Surprise Valley.

Lacustrine sediments deposited in the main Surprise Valley Landslide, when the graben was an enclosed basin without a drainage outlet.  This depression was subsequently breached by headward erosion of Bonita Creek.  These beds gently dip towards the depoaxis of the old graben.  From the samples recently recovered we were able to identify 18 pollens and spores, one freshwater algae, and fungal hyphae.

Questions or comments on this page?
E-mail Dr. J David Rogers at
or Conor Watkins at